1. Field of the Invention
The present invention relates to a substrate treatment apparatus and a substrate treatment method for treating a substrate. Examples of the substrate to be treated include semiconductor wafers, substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, ceramic substrates and substrates for solar cells.
2. Description of Related Art
In production processes for semiconductor devices, liquid crystal display devices and the like, substrate treatment apparatuses are used for treating substrates such as semiconductor wafers and glass substrates for the liquid crystal display devices.
A substrate treatment apparatus of a single substrate treatment type disclosed in JP-2006-344907A includes a spin chuck which horizontally holds and rotates a substrate, and a nozzle which spouts a treatment liquid having a temperature higher than a room temperature toward a center portion of an upper surface of the rotating substrate. The higher-temperature treatment liquid spouted from the nozzle reaches the center portion of the upper surface of the substrate and then spreads outward on the substrate by a centrifugal force. Thus, the higher-temperature treatment liquid is supplied over the entire upper surface of the substrate.
The higher-temperature treatment liquid supplied to the center portion of the rotating substrate is moved from the center portion of the substrate to a peripheral portion of the substrate by the centrifugal force. During the movement of the treatment liquid, the heat of the treatment liquid is removed by the substrate, so that the temperature of the treatment liquid is reduced. Further, the treatment liquid is partly evaporated while removing heat from the ambient environment during the outward movement of the treatment liquid on the substrate. Accordingly, the temperature of the treatment liquid is further reduced. The treatment liquid is more liable to be evaporated on the peripheral portion of the substrate than on the center portion of the substrate. This is because a speed at a given position of the rotating substrate is increased as a distance between the given position and the rotation axis of the substrate increases. Therefore, the treatment liquid has a lower temperature on the peripheral portion of the substrate than on the center portion of the substrate. Further, the peripheral portion of the substrate has a higher speed than the center portion of the substrate and, therefore, is more liable to be cooled than the center portion of the substrate. With such and other factors, the treatment liquid has a lower temperature on the peripheral portion of the substrate than on the center portion of the substrate, so that the uniformity of the temperature of the treatment liquid on the substrate is reduced. This reduces the uniformity of the treatment.
JP-2007-220989A discloses a method in which a cleaning liquid having a temperature lower by 1.0° C. to 5.0° C. than an ambient temperature is supplied to a lower surface of a substrate. In the method of JP-2007-220989A, however, it is impossible to uniformly treat the entire lower surface of the substrate, because the cleaning liquid is supplied only to the peripheral portion of the lower surface of the substrate.